Grain boundary pattern orientation calibration method and microscopic analysis equipment

Abstract

The invention discloses a grain boundary pattern orientation calibration method and microscopic analysis equipment. The grain boundary pattern orientation calibration method comprises the following steps: determining a grain orientation analysis area of a polycrystalline sample; obtaining and calibrating a Kikuchi pattern in the analysis area; determining a Kikuchi band vector of an uncalibrated Kikuchi pattern and a Kikuchi band vector of a Kikuchi pattern adjacent to the uncalibrated Kikuchi pattern, obtaining first data based on the Kikuchi band vector of the uncalibrated Kikuchi pattern, and obtaining second data based on the Kikuchi band vector of the Kikuchi pattern adjacent to the uncalibrated Kikuchi pattern; comparing the similarity between the first data and the second data; based on a comparison result, selecting a Kikuchi pattern with the highest similarity with the uncalibrated Kikuchi pattern as a matched pattern; and calculating and obtaining the orientation of the uncalibrated Kikuchi pattern based on the Kikuchi band of the uncalibrated Kikuchi pattern and the Kikuchi band of the matched pattern. Through the grain boundary pattern orientation calibration method provided by the invention, orientation calibration of the pattern at the grain boundary can be realized, and the problem of insufficient orientation analysis precision of a grain boundary transition region is solved.

Description

Technical Field

[0001] This application relates to the technical field of material microstructure characterization and crystallographic orientation analysis, and particularly to a method for calibrating grain boundary pattern orientations and a microscopic analysis device. Background Art

[0002] An Electron Back-scattered Diffraction (EBSD) instrument is a microscopic analysis device based on a Scanning Electron Microscope (SEM), capable of performing detailed structural analysis on the microstructure of materials. It detects the back-scattered electron signals generated on the surface of the sample, and then forms an Electron Back-scattered Pattern (EBSP). By analyzing the EBSP, crystallographic information of the sample can be extracted, helping researchers understand grain orientations, grain sizes, grain boundary characteristics, and stress and strain distributions in the material. EBSD is applicable not only to a variety of polycrystalline materials such as metal alloys, ceramics, and ores, but also has become an important tool for material microscopic analysis due to its high-efficiency data acquisition ability and high resolution (up to the nanometer level), and is widely used in academic research and industrial production.

[0003] The generation of EBSP is based on the interaction between the incident electron beam in the scanning electron microscope and the sample, which is the analysis basis of EBSD. The generation process of EBSP usually occurs in a thin layer about dozens of nanometers deep on the surface of the sample. When the incident electron beam bombards the surface of the sample, some electrons are strongly scattered and leave the sample to become back-scattered electrons. When these back-scattered electrons satisfy the Bragg diffraction condition (nλ = 2dsinθ) with specific crystal plane families in the sample, coherent scattering occurs, forming a diffraction phenomenon. This diffraction effect will produce Kikuchi bands on the receiving screen, that is, pairs of parallel straight lines. After these patterns (Kikuchi patterns) are captured by the camera and digitally processed, they can be used to analyze the crystallographic information of the sample, and high-spatial-resolution grain orientation and structure analysis can be achieved.

[0004] Among them, grain orientation is one of the main core contents of EBSD analysis, which describes the relative orientation of the crystal axes (such as

[100] -

[010] -

[001] ) in the rolling direction, transverse direction, and normal direction of the sample coordinate system; generally, the EBSP pattern is calibrated by EBSD, the Kikuchi bands in the EBSP pattern are analyzed, and using their geometric relationship with the crystal plane, it is calculated and represented by Euler angles or other crystallographic parameters.

[0005] However, in the prior art, due to the superposition of diffraction signals in the grain boundary transition region, it is easy to cause insufficient orientation analysis accuracy, thus affecting the reliability of material microstructure analysis, performance prediction, and phase identification.

[0006] Therefore, how to improve the technical defects existing in the prior art has always been an urgent problem to be solved by those of ordinary skill in the art. Summary of the Invention

[0007] The purpose of this application is to provide a method for calibrating the orientation of grain boundary patterns and a microscopic analysis device, which can realize the orientation calibration of patterns at grain boundaries, improve the accuracy of orientation analysis, and thus ensure the reliability of the microscopic structure analysis, performance prediction and phase identification of materials, providing important support for the microscopic structure research of materials.

[0008] The technical solution provided by the present invention is as follows:

[0009] A method for calibrating the orientation of grain boundary patterns, comprising the steps of:

[0010] Determine the grain orientation analysis region of the polycrystalline sample;

[0011] Obtain and calibrate the Kikuchi patterns within the analysis region;

[0012] Determine the Kikuchi band vectors of the uncalibrated Kikuchi patterns and their adjacent Kikuchi patterns, and based on the Kikuchi band vectors of the uncalibrated Kikuchi patterns, obtain the first data, and based on the Kikuchi band vectors of the Kikuchi patterns adjacent to the uncalibrated Kikuchi patterns, obtain the second data;

[0013] Compare the similarity between the first data and the second data;

[0014] Based on the comparison result, select the Kikuchi pattern with the highest similarity to the uncalibrated Kikuchi pattern as the matching pattern;

[0015] Based on the Kikuchi bands of the uncalibrated Kikuchi pattern and the matching pattern, calculate and obtain the orientation of the uncalibrated Kikuchi pattern.

[0016] In some embodiments, the step of determining the Kikuchi band vectors of the uncalibrated Kikuchi patterns and their adjacent Kikuchi patterns, and based on the Kikuchi band vectors of the uncalibrated Kikuchi patterns, obtaining the first data, and based on the Kikuchi band vectors of the Kikuchi patterns adjacent to the uncalibrated Kikuchi patterns, obtaining the second data, includes the steps of:

[0017] Based on the Kikuchi pattern calibration result, extract the uncalibrated Kikuchi patterns within the analysis region, and taking the uncalibrated Kikuchi patterns as the center, extract multiple adjacent Kikuchi patterns around them;

[0018] Based on the Hough transform, extract the Kikuchi band vectors of the uncalibrated Kikuchi patterns to obtain the first data;

[0019] Based on the Hough transform, extract the Kikuchi band vectors of the adjacent Kikuchi patterns to obtain the second data.

[0020] In some embodiments, the number of adjacent Kikuchi patterns extracted is six or eight.

[0021] In some embodiments, before extracting the Kikuchi band vectors of the uncalibrated Kikuchi pattern based on the Hough transform to obtain the first data, and extracting the Kikuchi band vectors of the adjacent Kikuchi patterns based on the Hough transform to obtain the second data, the method includes the steps of:

[0022] Determining the retrieval number of the Kikuchi bands in the Kikuchi pattern;

[0023] Based on the retrieval number, obtaining the Kikuchi bands in the uncalibrated Kikuchi pattern and the Kikuchi bands of multiple adjacent Kikuchi patterns adjacent thereto.

[0024] In some embodiments, extracting the Kikuchi band vectors of the uncalibrated Kikuchi pattern based on the Hough transform to obtain the first data, and extracting the Kikuchi band vectors of the adjacent Kikuchi patterns based on the Hough transform to obtain the second data includes:

[0025] Based on the Hough transform, identifying the center line position of the Kikuchi bands in the uncalibrated Kikuchi pattern, and obtaining the corresponding crystal plane normal vector as the first normal vector;

[0026] Based on the obtained first normal vector, determining a first matrix A formed by multiple first normal vectors, and the column vector A in the first matrix A i or the row vector A j forms the first data;

[0027] Based on the Hough transform, respectively identifying the center line positions of the Kikuchi bands in multiple adjacent Kikuchi patterns, and obtaining the corresponding crystal plane normal vectors as the second normal vectors;

[0028] Based on the obtained second normal vectors, determining a corresponding second matrix B formed by multiple second normal vectors n , and the multiple second matrices B n the column vector B in i or the row vector B j forms the second data.

[0029] In some embodiments, comparing the similarity between the first data and the second data includes the steps of:

[0030] Based on the formula M = A i × B i ′ or the formula M = A j × B j ′, calculating the first data and the second data;

[0031] Based on the calculation result, determining the similarity between the first data and the second data.

[0032] In some embodiments, determining the similarity between the first data and the second data based on the calculation result includes the steps of:

[0033] When M > 0.9995, the corresponding first data and second data are similar data;

[0034] When M ≤ 0.9995, the corresponding first data and second data are dissimilar data.

[0035] In some embodiments, selecting the Kikuchi pattern with the highest similarity to the uncalibrated Kikuchi pattern as the matching pattern based on the comparison result includes the steps of:

[0036] Record the number of similar data in the first matrix A and the second matrix B n ;

[0037] Among all the second matrices B n select the second matrix B with the largest number of similar data n as the approximate matrix;

[0038] If the number of approximate matrices is one, select the Kikuchi pattern corresponding to the approximate matrix as the matching pattern; if the number of approximate matrices is greater than one, sum up the M values of all the similar data corresponding to the approximate matrices, compare the sum results, determine the approximate matrix with the largest sum result, and select the Kikuchi pattern corresponding to it as the matching pattern.

[0039] In some embodiments, calculating and obtaining the orientation of the uncalibrated Kikuchi pattern based on the Kikuchi bands of the uncalibrated Kikuchi pattern and the Kikuchi bands of the matching pattern includes the steps of:

[0040] Based on the second matrix B corresponding to the matching pattern n , determine the similar data in the first matrix A;

[0041] Based on the similar data, select the corresponding first normal vector in the first matrix A;

[0042] Use the selected first normal vector as a subset for orientation calculation and recalculate the orientation;

[0043] Obtain the orientation of the uncalibrated Kikuchi pattern based on the calculation result.

[0044] This application also provides a microscopic analysis device that uses the grain boundary pattern orientation calibration method provided in any of the above embodiments to determine the grain orientation of a crystal sample.

[0045] The technical effect of this application is as follows:

[0046] 1. In this application, by performing similarity matching between the Kikuchi bands of the Kikuchi patterns that cannot be calibrated at the grain boundaries and the Kikuchi bands of the successfully calibrated Kikuchi patterns around them, a subset of Kikuchi bands belonging to a single grain is extracted for recalibration, achieving the orientation calibration of the Kikuchi patterns at the grain boundaries, effectively solving the problem of insufficient orientation analysis accuracy caused by diffraction signal superposition in the grain boundary transition region in the prior art, improving the reliability of the microstructure analysis, property prediction, and phase identification of materials, and providing important support for the microstructure research of materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments:

[0048] Figure 1 is the inverse pole figure of the EBSD plane distribution of yttrium-stabilized zirconia provided in an embodiment of this application;

[0049] Figure 2 is Figure 1 a partial enlarged schematic diagram of the black-framed part shown;

[0050] Figure 3 is Figure 2 the Kikuchi pattern marked by the blue frame and the dotted frame shown;

[0051] Figure 4 is Figure 3 the result output image of the position of the center line identified by the Hough transform of the Kikuchi pattern shown;

[0052] Figure 5 is Figure 3 the result output image of the matching of similar Kikuchi bands between the Kikuchi pattern marked by the blue frame and the Kikuchi patterns marked by the surrounding dotted frames shown;

[0053] Figure 6 is Figure 3 the calibration result of the Kikuchi pattern marked by the blue frame shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of this application. However, those skilled in the art should clearly understand that this application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of this application.

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will describe the specific implementation manners of the present application with reference to the accompanying drawings. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings, and other implementation manners can also be obtained.

[0056] To make the drawings concise, only the parts related to the present application are schematically shown in each drawing, and they do not represent the actual structure of the product. In addition, to make the drawings concise and easy to understand, in some drawings, components with the same structure or function are only schematically shown for one of them, or only one of them is marked. In this article, "one" not only means "only this one", but also means "more than one" situation.

[0057] It should also be further understood that the term "and / or" used in the specification and claims of the present application refers to any combination and all possible combinations of one or more of the related listed items, and includes these combinations.

[0058] In this article, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0059] In the embodiments shown in the drawings, the indication of directions (such as up, down, left, right, front, and back) is used to explain that the structures and movements of various components of the present application are not absolute but relative. When these components are in the positions shown in the drawings, these explanations are appropriate. If the descriptions of the positions of these components change, then the indication of these directions also changes accordingly.

[0060] In addition, in the description of the present application, the terms "first", "second", etc. are only used for distinguishing descriptions, and cannot be understood as indicating or implying relative importance.

[0061] Grain orientation is one of the main core contents of EBSD analysis. Generally, the EBSP pattern is calibrated by EBSD, the Kikuchi bands in the EBSP pattern are analyzed, and the geometric relationship between them and the crystal plane is used to calculate and obtain it. In the prior art, due to the superposition of diffraction signals in the grain boundary transition region, there are Kikuchi patterns that cannot be calibrated at the grain boundary, resulting in insufficient orientation analysis accuracy.

[0062] In response to this, the present application provides a method for calibrating the orientation of grain boundary patterns. This calibration method is applicable to EBSD and includes the following steps: 1) determining the grain orientation analysis region of the polycrystalline sample; 2) acquiring and calibrating the Kikuchi patterns within the analysis region; 3) determining the Kikuchi band vectors of the uncalibrated Kikuchi pattern and its neighboring Kikuchi patterns, and based on the Kikuchi band vector of the uncalibrated Kikuchi pattern, obtaining the first data, and based on the Kikuchi band vector of the Kikuchi pattern adjacent to the uncalibrated Kikuchi pattern, obtaining the second data; 4) comparing the similarity between the first data and the second data; 5) based on the comparison result, selecting the Kikuchi pattern with the highest similarity to the uncalibrated Kikuchi pattern as the matching pattern; 6) based on the Kikuchi band of the uncalibrated Kikuchi pattern and the Kikuchi band of the matching pattern, calculating and obtaining the orientation of the uncalibrated Kikuchi pattern.

[0063] In this embodiment, referring to Figure 1 , the analyst can first select an area of interest on the polycrystalline sample as the grain orientation analysis region for EBSD to perform EBSD surface distribution acquisition on the sample. Through the acquisition of EBSD, the analyst can obtain a series of Kikuchi patterns. After performing the calibration operation on them, due to the superposition of diffraction signals in the grain boundary transition region, there are still Kikuchi patterns that cannot be calibrated (i.e., uncalibrated) at the grain boundaries. Referring to Figure 2 , for the uncalibrated Kikuchi pattern, the closest neighboring Kikuchi patterns around it can be extracted. By obtaining the Kikuchi band vectors of the uncalibrated Kikuchi pattern and its neighboring Kikuchi patterns, performing calculations and similarity matching, and selecting the Kikuchi pattern with the highest similarity to the uncalibrated Kikuchi pattern as the matching pattern, a subset of Kikuchi bands belonging to the same grain can be screened out, successfully calibrating the orientation of the uncalibrated Kikuchi pattern at the grain boundary, greatly improving the orientation calculation accuracy, ensuring the reliability of the microstructure analysis, performance prediction, and phase identification of the material, and providing important support for the microstructure research of the material.

[0064] In a specific embodiment, when extracting the closest neighboring Kikuchi patterns around the uncalibrated Kikuchi pattern, multiple closest neighboring Kikuchi patterns can be extracted from the periphery with the uncalibrated Kikuchi pattern as the center, and then the Kikuchi band vectors of the uncalibrated Kikuchi pattern and its neighboring Kikuchi patterns can be extracted through the Hough Transform.

[0065] The Hough Transform is a simple geometric shape detection method, and its essence is to parameterize the geometric shapes in the image. For a straight line, the most commonly used parameterization method is to use the distance ρ from the origin of the coordinate system to the straight line and the angle θ between its direction vector and the positive x-axis direction to represent the position of the straight line. At this time, the equation of the straight line can be expressed as Based on this equation, a straight line in the traditional Cartesian coordinate system can be transformed into a point in the ρ-θ parameter space.

[0066] That is, in the above step 3), it further includes the steps of: based on the Kikuchi pattern calibration result, extracting the uncalibrated Kikuchi patterns in the analysis area, and taking the uncalibrated Kikuchi patterns as the center, extracting multiple adjacent Kikuchi patterns around them; extracting the Kikuchi band vectors of the uncalibrated Kikuchi patterns based on the Hough transform to obtain the first data; extracting the Kikuchi band vectors of the adjacent Kikuchi patterns based on the Hough transform to obtain the second data. Among them, the order between the step of obtaining the first data and the step of obtaining the second data can be interchanged.

[0067] In practical applications, the electron beam scans the sample point by point. According to the different scanning forms of the electron beam, the number of adjacent Kikuchi patterns extracted around is also different. For example, if scanned in a general square grid, there are eight adjacent Kikuchi patterns closest to the uncalibrated Kikuchi pattern, and these eight Kikuchi patterns are extracted; if the electron beam is scanned in a hexagonal grid, there are six adjacent Kikuchi patterns closest to the uncalibrated Kikuchi pattern, and these six Kikuchi patterns are extracted. Details are not described one by one here, and all are within the protection scope of this application.

[0068] Specifically, referring to Figure 2 and Figure 3 , taking the rectangular scan of the electron beam as an example, according to the calibration result, the uncalibrated Kikuchi patterns at the grain boundary are extracted. For each uncalibrated Kikuchi pattern K at the grain boundary, the eight closest calibrated Kikuchi patterns around it can be extracted, and are respectively denoted as Y1, Y2, Y3... Y8.

[0069] Before extracting the Kikuchi band vectors of the uncalibrated Kikuchi pattern K and its adjacent Kikuchi patterns through the Hough transform, it is also necessary to set the number of bands extracted for each Kikuchi pattern, that is, the retrieval number m of the Kikuchi bands in each Kikuchi pattern. Then, based on the retrieval number m, the Kikuchi bands in the uncalibrated Kikuchi pattern K and the Kikuchi bands of multiple adjacent Kikuchi patterns (Y1, Y2, Y3... Y8) are obtained.

[0070] Subsequently, the Kikuchi band vectors of the uncalibrated Kikuchi pattern K can be extracted based on the Hough transform to obtain the first data. Specifically, it may include the following steps: based on the Hough transform, identifying the center line position of the Kikuchi bands in the uncalibrated Kikuchi pattern K to obtain the corresponding crystal plane normal vector N E as the first normal vector; based on the obtained first normal vector, forming a matrix with the m crystal plane normal vectors retrieved from the uncalibrated Kikuchi pattern K, and making this matrix the first matrix A; if the form of the first matrix A is 3 rows and m columns, then the column vectors A i in the first matrix A form the above first data. If the form of the first matrix A is m rows and 3 columns, then the row vectors A j in the first matrix A form the above first data.

[0071] Conversely, after determining the number of detected Kikuchi bands m in each Kikuchi pattern, the Kikuchi band vectors of adjacent Kikuchi patterns (Y1, Y2, Y3... Y8) can also be extracted based on the Hough transform to obtain the second data. Specifically, the steps can be as follows: Based on the Hough transform, identify the center line positions of the Kikuchi bands in multiple adjacent Kikuchi patterns (Y1, Y2, Y3... Y8) respectively, and obtain the corresponding crystal plane normal vectors N E as the second normal vectors; based on the obtained second normal vectors, determine the corresponding second matrix B formed by multiple second normal vectors n (B1, B2, B3... B8); if the form of the second matrix B n (B1, B2, B3... B8) is 3 rows by m columns, then the column vectors B in the second matrix B n (B1, B2, B3... B8) form the above-mentioned second data. If the form of the second matrix B i (B1, B2, B3... B8) is m rows by 3 columns, then the row vectors B in the second matrix B n (B1, B2, B3... B8) form the above-mentioned second data. n (B1, B2, B3... B8) form the above-mentioned second data. j When calculating and performing similarity matching on the first data and the second data, the formula M = A

[0072] × B i ′ or the formula M = A i × B j ′ can be used. Determine the similarity between the first data and the second data based on the calculated M value, and thus determine the similarity between the Kikuchi band vectors of the uncalibrated Kikuchi pattern K and the Kikuchi patterns (Y1, Y2, Y3... Y8). For example, when M > 0.9995, it can be determined that the corresponding first data and second data are similar data; when M ≤ 0.9995, it is determined that the corresponding first data and second data are dissimilar data. j ′, and determine the similarity between the first data and the second data according to the calculated M value, thereby determining the similarity between the Kikuchi band vectors of the uncalibrated Kikuchi pattern K and the Kikuchi patterns (Y1, Y2, Y3... Y8). For example, when M > 0.9995, it can be determined that the corresponding first data and second data are similar data; when M ≤ 0.9995, it is determined that the corresponding first data and second data are dissimilar data.

[0073] Specifically, taking the column vectors A in the first matrix A i as the first data and the column vectors B in the second matrix B n (B1, B2, B3... B8) as the second data as an example, calculate the vectors in the first matrix A and the second matrix B i (B1, B2, B3... B8) through the formula M = A i × B i ′. When the M value > 0.9995, it is determined that the corresponding Kikuchi band A n (B1, B2, B3... B8) and the Kikuchi band B i are similar Kikuchi bands, otherwise they are dissimilar Kikuchi bands. i are similar Kikuchi bands, otherwise they are dissimilar Kikuchi bands.

[0074] Based on the comparison results, the Kikuchi pattern with the highest similarity to the uncalibrated Kikuchi pattern K can be selected as the matching pattern, which specifically includes the steps of: recording the first matrix A and the second matrix B n (B1, B2, B3... B8) the number of similar data; among all the second matrices B n (B1, B2, B3... B8), select the second matrix B with the largest number of similar data n as the approximate matrix; if the number of approximate matrices is one, select the Kikuchi pattern corresponding to the approximate matrix as the matching pattern; if the number of approximate matrices is greater than one, then sum the M values of all the similar data corresponding to the approximate matrices respectively, compare the summation results, determine the approximate matrix with the largest summation result, and use the Kikuchi pattern corresponding to it as the matching pattern.

[0075] In this embodiment, by recording the number of similar data in the first matrix A and the second matrix B n (B1, B2, B3... B8), it is possible to obtain how many Kikuchi lines similar to the first matrix A correspond to each second matrix B n , so as to facilitate counting the number of similar Kikuchi bands corresponding to the Kikuchi patterns (Y1, Y2, Y3... Y8) (as Figure 5 shown), which helps to select the matching pattern.

[0076] After determining the matching pattern, based on the second matrix B corresponding to the matching pattern n , determine the similar data in the first matrix A; then based on the similar data, select the corresponding first normal vector in the first matrix A; use the selected first normal vector as a subset of the orientation calculation, recalculate the orientation, and the orientation of the uncalibrated Kikuchi pattern K can be obtained.

[0077] In practical applications, generally, Euler angles are used to represent the orientation obtained by calibrating the Kikuchi pattern. The Euler angles are composed of three angles ψ1, φ, and ψ2, which are used to describe the rotation relationship between the unit cell and the external coordinate system. Specifically, ψ1 is the first rotation angle from the sample reference coordinate system to the crystallographic reference coordinate system, φ is the rotation angle around the new z-axis, and ψ2 is the second rotation angle to align the new x-y plane with the crystallographic coordinate system.

[0078] Through the matrix matching algorithm of the present application, for the patterns at the grain boundary where the Kikuchi bands on both sides overlap, similar strip matching can be performed on the adjacent patterns, so as to screen out the subset of Kikuchi bands belonging to the same grain, and perform orientation calibration on the patterns at the grain boundary where the Kikuchi pattern strips are clear but cannot be calibrated, thereby improving the calibration rate and orientation calculation accuracy of the Kikuchi pattern surface distribution data set.

[0079] In practical applications, this method for calibrating the orientation of grain boundary patterns can be used to evaluate the accuracy of orientation calculation when the theoretical orientation is unknown, or to select a reliable combination of Kikuchi poles in a Kikuchi pattern to obtain a high-precision orientation result. Without limitation, all of these are within the protection scope of this application.

[0080] Specifically, taking the orientation calibration of polycrystalline yttrium-stabilized zirconia in the cubic crystal system as an example, an EBSD system with the model of Oxford EBSD system and a scanning electron microscope with the model of Magellan400 under Thermo Fisher Scientific are used.

[0081] The analyst first selects the area of interest, collects the EBSD surface distribution data through the EBSD system, and obtains an inverse pole figure as shown in Figure 1 . In this figure, the area enclosed by each color represents a grain, and the white dots are the uncalibrated areas. Refer to Figure 2 , which is an enlarged view of the black frame area in Figure 1 . It can be seen from this enlarged view that there is an uncalibrated Kikuchi pattern K at the grain boundary. Further refer to Figure 3 , extract the uncalibrated Kikuchi pattern K (the Kikuchi pattern marked by the blue frame) at the grain boundary and its eight nearest Kikuchi patterns Y1 - Y8 (the Kikuchi patterns marked by the dashed frames), and identify the positions of the centerlines of the Kikuchi bands by performing the Hough transform on the nine Kikuchi patterns shown in Figure 3 . Specifically, first set the number of Kikuchi bands to be searched as 10, and the result shown in Figure 4 can be obtained. Then, identify this result according to the Hough transform to obtain the crystal plane normal vectors of the first matrix A of the uncalibrated Kikuchi pattern K and the crystal plane normal vectors of the second matrix B of the Kikuchi patterns Y1 - Y8. Among them, the crystal plane normal vectors of the first matrix A of the uncalibrated Kikuchi pattern K are shown in Table 1.

[0082] Table 1 Crystal plane normal vectors of the first matrix A

[0083]

[0084] Subsequently, calculate the M value between the first matrix A and the second matrices B of the Kikuchi patterns Y1 - Y8 to obtain the number of similar Kikuchi bands corresponding to each Kikuchi pattern. Specifically, refer to Figure 5Among them, the number of similar Kikuchi bands of Kikuchi patterns Y7 and Y8 is 9 each, which is the largest number of similar Kikuchi bands. Thus, the M values of the 9 similar Kikuchi bands in Kikuchi patterns Y7 and Y8 need to be summed respectively. After calculation, the sum of the M values of the 9 similar Kikuchi bands of Kikuchi pattern Y7 is 8.999607, and the sum of the M values of the 9 similar Kikuchi bands of Kikuchi pattern Y8 is 8.999614. Therefore, Kikuchi pattern Y8 is finally selected as the matching pattern, and the second matrix B8 corresponding to Kikuchi pattern Y8 is shown in Table 2.

[0085] Table 2 Normal vectors of crystal planes of the second matrix B8 corresponding to Kikuchi pattern Y8

[0086]

[0087] Correspondingly, for the first matrix A and the second matrix B8 corresponding to Kikuchi pattern Y8, the calculated M value results are shown in Table 3.

[0088] Table 3 Calculation results of M values

[0089]

[0090] According to the calculation results of the M values, the 9 Kikuchi bands A1, A2, A3, A4, A5, A6, A8, A9, A10 with similar bands are grouped into a new subset, and the orientation of Kikuchi pattern K is calibrated based on this subset. See Figure 6 , which shows the crystal planes corresponding to the 9 Kikuchi bands A1, A2, A3, A4, A5, A6, A8, A9, A10 in Kikuchi pattern K, and the calibrated orientation values are (-91.16°, 99.57°, -75.07°).

[0091] According to the above embodiments, it can be known that in this application, by calculating a new subset formed by the similar Kikuchi bands of the uncalibrated pattern and the surrounding patterns, the uncalibrated pattern at the grain boundary can be successfully calibrated, solving the problem that although the Kikuchi bands at the grain boundary are clear, they cannot be calibrated due to the overlap of Kikuchi patterns, and improving the calibration rate of the EBSD surface distribution.

[0092] This application also provides a microscopic analysis device, namely the above EBSD analysis device, which uses the grain boundary pattern orientation calibration method provided in any of the above embodiments to determine the grain orientation of the crystal sample.

[0093] In the above embodiments, the descriptions of each embodiment have their own focuses. For parts not detailedly described or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0094] It should be noted that the above embodiments can be freely combined as needed. The above are only the preferred embodiments of this application. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of this application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of this application.

Claims

1. A method for calibrating the orientation of grain boundary patterns, characterized in that, Including the steps: Determine the grain orientation analysis area of the polycrystalline sample; Obtain and calibrate the Kikuchi patterns within the analysis area; Determine the Kikuchi band vectors of the uncalibrated Kikuchi pattern and its adjacent Kikuchi patterns, and based on the Kikuchi band vectors of the uncalibrated Kikuchi pattern, obtain the first data, and based on the Kikuchi band vectors of the Kikuchi patterns adjacent to the uncalibrated Kikuchi pattern, obtain the second data; Compare the similarity between the first data and the second data; Based on the comparison result, select the Kikuchi pattern with the highest similarity to the uncalibrated Kikuchi pattern as the matching pattern; Based on the Kikuchi bands of the uncalibrated Kikuchi pattern and the Kikuchi bands of the matching pattern, calculate and obtain the orientation of the uncalibrated Kikuchi pattern.

2. The grain boundary pattern orientation calibration method according to claim 1, wherein The step of determining the Kikuchi band vectors of the uncalibrated Kikuchi pattern and its adjacent Kikuchi patterns, and based on the Kikuchi band vectors of the uncalibrated Kikuchi pattern, obtaining the first data, and based on the Kikuchi band vectors of the Kikuchi patterns adjacent to the uncalibrated Kikuchi pattern, obtaining the second data, includes the steps: Based on the Kikuchi pattern calibration result, extract the uncalibrated Kikuchi patterns within the analysis area, and with the uncalibrated Kikuchi pattern as the center, extract multiple adjacent Kikuchi patterns around it; Extract the Kikuchi band vectors of the uncalibrated Kikuchi pattern based on the Hough transform to obtain the first data; Extract the Kikuchi band vectors of the adjacent Kikuchi patterns based on the Hough transform to obtain the second data.

3. The method for calibrating the orientation of the grain boundary pattern according to claim 2, wherein The number of adjacent Kikuchi patterns extracted is six or eight.

4. The method for calibrating the grain boundary pattern orientation according to claim 2, wherein Before the step of extracting the Kikuchi band vectors of the uncalibrated Kikuchi pattern based on the Hough transform to obtain the first data; and extracting the Kikuchi band vectors of the adjacent Kikuchi patterns based on the Hough transform to obtain the second data, includes the steps: Determine the retrieval number of the Kikuchi bands in the Kikuchi pattern; Based on the retrieval number, obtain the Kikuchi bands of the uncalibrated Kikuchi pattern and the Kikuchi bands of multiple adjacent Kikuchi patterns thereof.

5. The grain boundary pattern orientation calibration method according to claim 3, wherein The step of extracting the Kikuchi band vectors of the uncalibrated Kikuchi pattern based on the Hough transform to obtain the first data; The step of extracting the Kikuchi band vectors of the adjacent Kikuchi patterns based on the Hough transform to obtain the second data, includes: Based on the Hough transform, identify the center line position of the Kikuchi band in the uncalibrated Kikuchi pattern, and obtain the corresponding crystal plane normal vector as the first normal vector; Based on the acquired first normal vector, a first matrix A formed by a plurality of first normal vectors is determined, wherein the column vector A in the first matrix A is i or row vector A j forming the first data; Based on the Hough transform, respectively identify the center line positions of the Kikuchi bands in multiple adjacent Kikuchi patterns, and obtain the corresponding crystal plane normal vectors as the second normal vectors; Based on the obtained second normal vectors, determine the corresponding second matrix B formed by a plurality of second normal vectors n , a plurality of the second matrices B n wherein the column vectors B i or the row vectors B j form the second data.

6. The method for calibrating the grain boundary pattern orientation according to claim 5, wherein The step of comparing the similarity between the first data and the second data, includes the steps: Based on the formula M = A i ×B i ′ or the formula M = A j ×B j ′, calculate the first data and the second data; Based on the calculation result, determine the similarity between the first data and the second data.

7. The grain boundary pattern orientation calibration method according to claim 6, wherein The step of determining the similarity between the first data and the second data based on the calculation result, includes the steps: When M > 0.9995, the corresponding first data and second data are similar data; When M ≤ 0.9995, the corresponding first data and second data are non-similar data.

8. The method for calibrating the grain boundary pattern orientation according to claim 7, characterized in that, The step of selecting the Kikuchi pattern with the highest similarity to the uncalibrated Kikuchi pattern as the matching pattern based on the comparison result, includes the steps: Record the number of similar data in the first matrix A and the second matrix B n ; Among all the second matrices B n select the second matrix B with the largest number of similar data n as the approximate matrix; If the number of approximate matrices is one, select the Kikuchi pattern corresponding to the approximate matrix as the matching pattern; if the number of approximate matrices is greater than one, sum up the M values of all similar data corresponding to the approximate matrices, compare the summation results, determine the approximate matrix with the largest summation result, and use the Kikuchi pattern corresponding to it as the matching pattern.

9. The method for calibrating the grain boundary pattern orientation according to claim 8, wherein Calculating and obtaining the orientation of the uncalibrated Kikuchi pattern based on the Kikuchi bands of the uncalibrated Kikuchi pattern and the Kikuchi bands of the matching pattern includes the steps of: Based on the second matrix B corresponding to the matching pattern n , determine the similar data in the first matrix A; Based on the similar data, select the corresponding first normal vector in the first matrix A; Taking the selected first normal vector as a subset of the orientation calculation, recalculate the orientation; Obtain the orientation of the uncalibrated Kikuchi pattern based on the calculation result.

10. A microscopic analysis device, characterized in that, Use the grain boundary pattern orientation calibration method described in any one of claims 1-9 to determine the grain orientation of the crystal sample.

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